1. Field of the Invention
This invention relates to automatic extraction of capsuled samples of fluid, and more particularly, to the automatic and periodic extraction of capsuled samples of oil well drilling fluids during the course of drilling oil and gas wells. The analysis of oil and gas well drilling fluid in order to determine the amount and kind of hydrocarbon components entrained in the fluid during the course of drilling is of prime concern to those who are involved in "mud logging" of drilled wells. For many reasons pertinent to the drilling operation it is important to obtain an accurate, quantitative measurement of hydrocarbons contained in the drilling fluid at the time the drill bit penetrates a particular stratum or interval under measurement. Not only is it important to compile this information when the well is being drilled, but it is also desirable to maintain a sealed, representative sample of the drilling fluid which can be stored and used in subsequent analysis for future reference. Furthermore, it is important to obtain such capsuled samples over a relatively long time period on an automated basis in order to provide an accurate and inexpensive log of the drilling operation.
2. Description of the Prior Art
In mud logging operations undertaken pursuant to the drilling of an oil or gas well, the gas trap or extractor in the mud pumping system is normally located at the shale shaker. A portion of the pumped drilling fluid is diverted through the gas trap to effect release of all or part of the hydrocarbons or other gases entrained in the drilling fluid, and the resulting gas-air mixture is continually drawn from the trap through a hose to the mud logging unit. At this unit the mixture is analyzed on a continuous basis by means of a hot wire detector, or by batch methods using such techniques as gas chromotography, hydrogen flame detection, or mass spectroscopy, and the amount of gas in the fluid is observed and recorded. Normally, there is no method for storing the samples so tested for later examination, and no known substantive method presently exists to prove whether any gas was, in fact, present in the drilling fluid under circumstances where the trap malfunctions and no gas is extracted. Under such circumstances, it is generally assumed that no gas was present in the drilling fluid and the results are so recorded. Furthermore, the conventional gas trap technique of extracting hydrocarbons and other gases in the drilling mud are frequently limited by the physical properties of the drilling fluid and mud pumping system in terms of physically locating the trap in the system for continuous and efficient operation.
Accordingly, it is an object of this invention to provide a new and improved process and apparatus for extracting encapsulated samples of oil and gas well drilling fluid from which a complete and periodic hydrocarbon or other gas analysis can be made either at the time of extraction or in the future.
It is a further object of this invention to provide an oil and gas well drilling fluid sample extracting apparatus which is mounted between the bell nipple and the shale shaker in the drilling rig and functions to trap and encapsulate samples of the drilling fluid pumped between the bell nipple and the shale shaker screen for current or future analysis.
Another object of this invention is to provide a sampling apparatus and procedure which are capable of automatically providing multiple capsules and encapsulated samples from a stream of oil or gas well drilling fluid on a periodic basis by extracting empty capsules from a storage container, immersing the capsules in a stream of the drilling fluid to be tested and storing the capsules in sealed condition for immediate or subsequent analysis.
Yet another object of this invention is to provide a method and apparatus for providing sealed capsules containing drilling fluid samples which may be chronologically stored in order that at some future time a specified drilling fluid sample or samples may be identified as to the time, date and depth of drill penetration which occurred when the oil or gas well was drilled.
A still further object of this invention is to provide a method and apparatus for extracting samples of oil and gas well drilling fluid on a continuous basis without the necessity of interrupting any of the drilling operations.
Another object of the invention is to provide a method and apparatus for securing sealed, encapsulated samples of oil or gas well drilling fluid on a periodic basis and automatically, in such a manner as to permit identification of each capsule sample with the depth of the drill bit penetration, thus identifying the strata or interval from which the particular sample in question originated.
Still another object of the invention is to provide an apparatus and method which is capable of producing multiple, encapsulated samples of drilling fluid or mud on an extended time basis, thus creating data for the production of the log of the well such that the resulting log provides meaningful information as to the well characteristics.
Yet another object of the invention is to provide a method and apparatus for securing capsule samples of drilling fluid from which a quantitative measurement of hydrocarbons and other gases in the drilling fluid can be determined relative to the amount of hydrocarbons entering the fluid at the time the drill bit penetrated a particular interval or strata under measurement.